DEPUTY First Minister Nicola Sturgeon confirmed a referendum Bill and a law allowing 16 and 17-year-olds to vote in the independence ballot will be introduced to Holyrood at the beginning of next year.

THE leaders of the Yes and No ­campaigns have vowed not to turn the ­independence poll ­campaign into a ­slanging match.

Deputy First Minister Nicola Sturgeon and former chancellor Alistair Darling said Scots expect politicians to debate the country’s future with passion and respect.

Their calls came amid fears the debate will become increasingly bitter and bad-tempered.

Sturgeon spoke out as she ­confirmed a referendum Bill would be introduced to Holyrood early next year, along with a law to allow 16 and 17-year-olds to take part in the ballot in 2014.

She urged campaigners on both sides to ensure the debate takes place “in a positive way that ­encourages the people of Scotland to turn out and make an informed choice on their future”.

Sturgeon added: “Now that the legal basis of the referendum has been confirmed through the ­historic Edinburgh Agreement, the debate that follows on the ­substance of the argument must be a positive one – the people of ­Scotland deserve no less.

“I want to see – on both sides of the debate, and whatever we think Scotland’s constitutional future should be – everyone involved engaging in a positive way that encourages the people of ­Scotland to turn out and make an informed choice on their future. She made the plea as ­Darling, who is spearheading the campaign to keep Scotland in the UK, claimed the Nationalists had been “exposed as ill-prepared for this historic debate” and had “not thought through their answers to the really big ­questions”.

Darling, who is heading the ­Better Together campaign, said those who raised questions about the impact of independence were too often “accused of being negative or ­scaremongering”.

He said 2013 would be “the year where we debate whether the ­people of the UK are to stick together or whether we are going to break apart”.

And he argued: “We need a debate which is conducted in an atmosphere of respect on all sides.”

The two rival politicians spoke at the end of a year in which ­Sturgeon said a lot had been achieved to “ensure that Scotland can hold a referendum made in Scotland that is beyond effective legal challenge”.

First Minister Alex Salmond launched the Scottish Government’s consultation on the ­referendum in January.

In October, after months of talks between Holyrood and ­Westminster, Prime Minister David Cameron and Salmond signed a deal on the staging of the vote.

Since then, the SNP have been on the back foot as their policy ­positions on Europe, the pound and Nato came under sustained scrutiny.

Darling pledged to “continue to make the case that we are better together in the UK”. The Labour MP said: “This will be a choice between continuing the success of ­devolution within the UK and the risk of breaking away from ­Britain.

“It is a choice between ­concentrating on getting our ­economy back on track or years more instability and uncertainty as we turn our backs on our biggest market and closest allies. It will also be a choice between the values of unity and division.”

He said a question as “important and irreversible” as Scotland’s ­constitutional future “needs a full and detailed debate”.

Darling added: “We need a debate which is conducted in an ­atmosphere of respect on all sides.

“Too often those who raise ­questions, without even taking sides on independence, are accused of being negative or scaremongering, when all they want to know are the answers to basic ­questions.”

He said: “We will be making the ­positive case that, on our small island, we have more in common than divides us, that Scotland has more to gain by working together with the rest of the UK ­family than by turning against each other, that our best future remains together rather than apart.”